Audio output apparatus capable of controlling temperature of voice coil and method thereof

Abstract

An audio output apparatus and a method are provided, which includes calculating a temperature value of a voice coil of the audio output apparatus using a heat transfer model algorithm, in response to power being supplied to the voice coil; adjusting an output level of an audio signal by determining a gain value to adjust the output level of the audio signal according to the calculated voice coil temperature value, and outputting the audio signal with the adjusted output level.

What is claimed is: 
     
       1. A method of outputting audio, the method comprising:
 calculating a temperature value of a voice coil of an audio output apparatus using a heat transfer model algorithm, in response to power being supplied to the voice coil; 
 calculating a temperature value of the voice coil using an algorithm transformed from the heat transfer model algorithm in response to power being re-supplied to the voice coil and setting the temperature value of the voice coil calculated using the transformed algorithm to be an initial temperature of the voice coil; 
 adjusting an output level of an audio signal by determining a gain value to adjust the output level of the audio signal depending on whether or not a temperature value of the voice coil calculated based on the set initial temperature value is within a threshold interval; and 
 outputting the audio signal with the adjusted output level. 
 
     
     
       2. The method of  claim 1 , wherein the initial temperature value of the voice coil is a temperature value of the voice coil at a time point of power being re-supplied to the voice coil of the audio output apparatus after a cut off of an initial power supply. 
     
     
       3. The method of  claim 1 , wherein the heat transfer model algorithm is expressed by:
     T ( s )/ P ( s )=( R   TV   R   TM ( C   TV   +C   TM ) s +( R   TV   +R   TM ))/(( R   TV   R   TM   C   TV   C   TM ) s   2 +( R   TV   C   TV   +R   TM   C   TM ) s+ 1), 
 where P(s) denotes output power relative to the audio signal, T(s) is temperature value of the voice coil, R TV  is heat resistance of the voice coil, C TV  is heat capacity of the voice coil, R TM  is heat resistance of a permanent magnet, and C TM  is heat capacity of the permanent magnet. 
 
     
     
       4. The method of  claim 1 , wherein the adjusting comprises:
 determining whether the temperature value of the voice coil calculated based on the initial temperature value is in a first threshold interval; and 
 in response to determining that the temperature value of the voice coil calculated using the initial temperature value exceeds the first threshold interval, determining the gain value to adjust the output level of the audio signal based on a first gain value that is lower than a reference gain value. 
 
     
     
       5. The method of  claim 4 , wherein the adjusting further comprises, in response to the temperature value of the voice coil calculated using the initial temperature value being in a heat resistant limit interval, determining the gain value to adjust the output level of the audio signal based on a second gain value that is lower than the first gain value. 
     
     
       6. The method of  claim 5 , wherein the heat resistant limit interval is a temperature interval exceeding a melting point of the voice coil, and the second gain value is in proportion to a difference between the temperature value of the voice coil calculated using the initial temperature value and a highest temperature value of the first threshold interval. 
     
     
       7. The method of  claim 5 , wherein the calculating comprises measuring the temperature of the voice coil continuously at a predetermined interval, and
 wherein the adjusting further comprises:
 determining whether the temperature value of the voice coil calculated using the initial temperature value is below a second threshold interval, in a state that the audio signal is output at an output level adjusted based on the first or second gain value; and 
 in response to determining that the temperature value of the voice coil calculated using the initial temperature value is between the first and second threshold intervals, maintaining the first or second gain value, or in response to determining that the temperature value of the voice coil calculated using the initial temperature value is below the second threshold interval, determining the gain value to adjust the output level of the audio signal based on a third gain value that is higher than the first gain value. 
 
 
     
     
       8. The method of  claim 7 , wherein the third gain value is within a narrower interval than that of the first gain value. 
     
     
       9. An audio output apparatus comprising:
 an input configured to receive an audio signal; 
 a signal processor configured to process the audio signal; 
 an output configured to output the processed audio signal; 
 a controller configured to calculate a temperature value of a voice coil of an audio output apparatus using a heat transfer model algorithm, in response to power being supplied to the voice coil, calculate a temperature value of the voice coil using an algorithm transformed from the heat transfer model algorithm temperature value, in response to power being re-supplied to the voice coil, set the temperature value of the voice coil calculated using the transformed algorithm to be an initial temperature of the voice coil, and determine a gain value to adjust an output level of the audio signal depending on whether or not a temperature value of the voice coil calculated based on the set in temperature value is within a threshold value, and adjust the output level of the processed audio signal. 
 
     
     
       10. The audio output apparatus of  claim 9 , wherein the initial temperature value of the voice coil is a temperature value of the voice coil at a time point of power being re-supplied to the voice coil of the audio output apparatus after a cut off of an initial power supply. 
     
     
       11. The audio output apparatus of  claim 9 , wherein the heat transfer model algorithm is expressed by:
     T ( s )/ P ( s )=( R   TV   R   TM ( C   TV   +C   TM ) s +( R   TV   +R   TM ))/(( R   TV   R   TM   C   TV   C   TM ) s   2 +( R   TV   C   TV   +R   TM   C   TM ) s+ 1), 
 where P(s) denotes output power relative to the audio signal, T(s) is temperature value of the voice coil, R TV  is heat resistance of the voice coil, C TV  is heat capacity of the voice coil, R TM  is heat resistance of a permanent magnet, and C TM  is heat capacity of the permanent magnet. 
 
     
     
       12. The audio output apparatus of  claim 9 , wherein, in response to the temperature value of the voice coil calculated using the initial temperature value exceeding a first threshold interval, the controller determines the gain value to adjust the output level of the audio signal based on a first gain value that is lower than a reference gain value. 
     
     
       13. The audio output apparatus of  claim 12 , wherein, in response to the temperature value of the voice coil calculated using the initial temperature value being in a heat resistant limit interval, the controller determines the gain value to adjust the output level of the audio signal based on a second gain value that is lower than the first gain value. 
     
     
       14. The audio output apparatus of  claim 13 , wherein the heat resistant limit interval is a temperature interval exceeding a melting point of the voice coil, and the second gain value is in proportion to a difference between the temperature value of the voice coil calculated using the initial temperature value and a highest temperature value of the first threshold interval. 
     
     
       15. The audio output apparatus of  claim 13 , wherein the controller determines whether the temperature value of the voice coil calculated using the initial temperature value is below a second threshold interval, in a state that the audio signal is output at an output level adjusted based on the first or second gain value, and
 maintains the first or second gain value in response to the temperature value of the voice coil calculated using the initial temperature value being between the first and second threshold intervals, or determines the gain value to adjust the output level of the audio signal based on a third gain value that is higher than the first gain value in response to determining that the temperature value of the voice coil calculated using the initial temperature value is below the second threshold interval. 
 
     
     
       16. The audio output apparatus of  claim 15 , wherein the third gain value is within a narrower interval than that of the first gain value. 
     
     
       17. A method for outputting audio, the method comprising:
 calculating a temperature value of a voice coil of an audio output apparatus using a heat transfer model algorithm, in response to power being supplied to the voice coil; 
 calculating a temperature value of the voice coil using an algorithm transformed from the heat transfer model algorithm in response to power being re-supplied to the voice coil and setting the temperature value of the voice coil calculated using the transformed algorithm to be an initial temperature of the voice coil; 
 adjusting an audio signal by using a gain value determined depending on whether or not a temperature value of the voice coil based on the set initial temperature value is within a threshold value; and 
 outputting the adjusted audio signal. 
 
     
     
       18. The method of  claim 17 , wherein the heat transfer model algorithm is expressed by:
     T ( s )/ P ( s )=( R   TV   R   TM ( C   TV   +C   TM ) s +( R   TV   +R   TM ))/(( R   TV   R   TM   C   TV   C   TM ) s   2 +( R   TV   C   TV   +R   TM   C   TM ) s+ 1), 
 where P(s) denotes output power relative to the audio signal, T(s) is temperature value of the voice coil, R TV  is heat resistance of the voice coil, C TV  is heat capacity of the voice coil, R TM  is heat resistance of a permanent magnet, and C TM  is heat capacity of the permanent magnet.